Recoil mechanism



Sept. 5, 1950 c. slMPsoN macon. MECHANISM 2 Sheets-Sheet v1 Filed Jan. 5, 1946 lllllllll l M M W gm.

Sept. 5, 1950 c. E. slMPsoN 2,520,971

BECOIL MECHANISM Filed Jan. 3, 1946 2 Sheets-Sheet 2 l: Inra-nde E- 51m- F 5ml-L Patented Sept. 5, 1950 UNITED sTATEs PATENT OFFICE (Granted under the act of March 3, 1883, as`

amended April 30, 1928; 370 O. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a recoil mechanism for larger caliber firearms than can be fired from the shoulder without auxiliary recoil absorbing means.

In firing large caliber firearms such as mortars, which are designed to operate from the shoulder, there is always the problem of dissipating a suiiicient proportion of the energy of recoil so that the residual energy can be safely or comfortably absorbed by the operator. Various methods employed for reducing the residual energy of recoil have met with indifferent success, some having failed to reduce the energy of recoil to within practical limits, some having been too complicated, and some having been undependable in operation.

It is therefore the purpose of this invention to provide a recoil mechanism that will dissipate a considerable proportion of the energy of recoil, that will be reasonably simple, and that will be dependable in operation.

The specilic nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a fragmentary right side elevational view of the shoulder mortar partly broken away to show the firing mechanism.

Fig. 2 is an enlarged detail view of the firing mechanism shown in the cocked position.

Fig. 3 is a longitudinal sectional View of Fig. 1 taken along the line 3 3.

Fig. 4 is an enlarged cross sectional view taken along the line 4-4 of Fig. 2.

The invention is illustrated in connection with a mortar consisting essentially of a housing assembly in which is slidably engaged a mortar tube and breech cap arranged to recoil against a return spring. A gas-actuated brake is provided in the breech cap and operates against the inner wall of the housing.

For the purposes of illustration, this invention Will be described primarily in its relation to ordnance pieces, such as mortars, which have open firing chambers. However, it is to be understood that the apparatus and the function thereof as herein described are, with only minor changes, equally adaptable for other types of mechanism in which fluid pressure is arranged to actuate a braking mechanism for checking the travel of an element.

The assembled housing comprises a cylinder I, a rearwardly extending cyclinder extension I0, an-adapter-bushing 5 whichis provided and adapted for securing cylinder extension I0 to the cylinder I, and a forwardly extending guide sleeve 24 threadably secured to cylinder I.

Cylinder I is provided with a plurality of circumferential reinforcing ribs 2, longitudinally spaced and arranged as shown in Fig. 1. A hammer slot 4 is provided in the underside for cooperation with a hammer as will be shown later.

The adapter-bushing 5 is threadably engaged to the rearward Aend of cylinder I and to the forward end of cylinder extension I 0 and is arranged to secure cylinder I and cylinder extension I0 in fixed coaxial relation. A set screw 3 is provided for securing cylinder I and cylinder extension I0 against rotational movement relative to each other. An annular bearing ring 16 is provided Vinside of and integral with adapterbushing y5 for a purpose to appear later. Adapterbushing 5 is., provided with recesses 'I for lightening purposes. Y

An adapter-cap I3 lis provided for securing cylinder extension I0 toa shoulderrest I8. This adapter cap I3 is'thread-ably engaged to cylinder extension I0. An annular recess I5 is provided in the forward or inside face of adapter-cap I3 for a purpose to appear later, and an axial recess I6 is provided for lightening the cap. The shoulder rest I8 is secured by any convenient means to the back of adapter-cap I 3. The `shoulder rest I8 is composed of a back plate I9 and a cushion 20 as shown in Fig. 1. A set screw 2I is provided for securing adapter capy I3 in fixed relation to cylinder extension I0.

Guide sleeve 24 is threadably secured in the forward end of cylinder I and is locked in xed relation therewith by a set screw 25 provided for that purpose. A bearing 26 is provided in the thereby preventing tube 3U from rotational movement in guide sleeve 24.

Breech cap 35 is in the general form of a cylindrical cup, the side Wall 36 being threadably engaged onto tube 30 'and secured thereto by staking. The base 31 of breech cap 35 is substantially of greater diameter than the remainder of |cap 35 as shown in Fig 3, and is provided with a plurality of spaced chordal slots 38 (two diametrically opposite slots of equal depth in the preferred embodiment). A cylindrical recess 39 is radially provided in the breech'cap 35 in communication with the center of each chordal slot 38. Apertures 40 are provided in base 31 to connect cylindrical recesses 39 to the interior of tube 30 :which serves as the firing chamber 4I of the mortar. A brake shoe 44 in the form of a chordal segment is adapted to slidably fit in eac'h chordal slot 38 in breech cap 35. A piston 45 is slidably inserted within a suitable hole provided in each brake shoe 44. The head of each piston 45 rests within respective cylindrical recesses 39. The arcuate face 41 of brake shoe 44 is arranged to be concentric with the inner surface of cylinder I. Brake shoe 44 and piston 45 are arranged with relation to breech cap 35 so that gas pressure developed in firing chamber 4I is transmitted through aperture 4'0 to piston 45 thereby forcing brake shoe 44 against the inner surface of cylinder I.

An axial ring pin hole consisting of an vaperture 50 and an orifice 5| extends through breech cap base 31. A boss 52 is provided on the rearward :face of breech .cap base 31 coaxial with iiring pin aperture 50. A screw collar 53 is secured to boss 52 by suitable threads and is provided to maintain a iiring pin 55 within firing pin aperture 58. A firing pin spring 56 is provided for resiliently maintaining firing pin 55 in a normally retracted position. A longitudinal cam cut 42 is provided underneath breech cap 35 for a purpose to be shown later.

A breech-cap extension sleeve 6I) with terminal bearing ribs I and 62 is -attached to the rearward face of breech cap 35 by pins 3 so that a hammer slot 54 provided in the bottom of sleeve 60 will be maintained in longitudinal alignment with cam cut 42 in the breech cap 35.

A bushing 58 is provided in the rearward end of breech-cap extension sleeve 60, the bushing having a longitudinal extension G9 :arranged coaxial with cylinder I. Another tubular spring guide 1I! is threadably secured on extension 59 and extends rearwardly to be slidably engaged in annular bearing ring 6 in adapter-bushing 5. Apertures 1I are provided in bushing 63 to permit free flow of air therethrough, and cushion 12 is provided on the rearward face of the bushing for a purpose to be shown.

A recoil spring 15 is provided for assembly between bushing 68 and adapter-cap I3, lying irlside outer spring guide as shown in Fig. 3. The rearward end of spring is engaged in the annular recess I5 in adapter 'cap I3. Also an inner tubular spring guide 11 is secured in annular recess l5 inside of spring 15 and extends forward to a point slightly within the rearward end of outer guide 10.

Since breech-cap extension sleeve 6B is pinned to breech cap 35, which in turn is staked to the tube 30 and the tube is held in angular alignment with guide sleeve 24 by engagement of cylindrical key 28 in key-way 3| in the tube, and since guide sleeve 24 is secured in position in cylinder I by means of set screw 25, it follows that hammer slot 4 in cylinder I and hammer slot 64 in breech cap extension sleeve 60 and cam cut 42 in breech cap 35 are maintained in longitudinal alignment thereby at all times.

A pistol grip 80 is provided on the underside of cylinder I, together with a trigger 8| and trigger mechanism of conventional type adapted to the particular application. A hammer 82 is pivotally mounted just below the forward portion of hammer slot 4 in the cylinder and is arranged so that in the cocked position it is locked horizontally below the Slot by a sear 84. Hammer 82 is arranged to be actuated by a torsion spring 83 for upward pivoting movement so as to strike firing pin when sear 84 is depressed by pulling trigger 8i.

In operation the firing mechanism is cocked by forcing the mortar tube 30 inwardly until hammer 82 is forced downward to a horizontal position by the camming action of cam cut 42 in breech cap 35. A mortar shell (not shown) is then placed in the mortar tube 3U and the mortar held to the shoulder and aimed as desired. When the trigger SI is pulled back, hammer 82 is released and is pivoted up through hammer slots 4 and 64 in cylinder I and breech cap extension sleeve respectively to strike firing pin 55 which is thereby driven forward to fire the mortar shell (not shown).

The high gas pressure developed in iiring chamber 4I forces the mortar tube and breech cap assembly rearwardly against the force of recoil spring 15, causing bushing 68 and spring guide 10 to move rearwardly. Spring guide 1D, being outside of spring 15, slides rearward through bearing ring 5 in adapter-bushing 5 in telescoping relation with respect to inner spring guide 11, cushion 12 engaging the forward face of adapter-bushing 5 at the end of the stroke to cushion the impact thereon.

At the same time, the entrapped gases expand through apertures 40 in breech cap 35 into radial cylindrical recesses 39 and exert pressure in a radial direction outwardly against pistons 45, thereby forcing brake shoes 44 against the wall of cylinder I to cause a large quantity of frictional resistance which will be proportional to the product of the gas pressure developed and the period of application. As soon as the mortar shell has left mortar tube 30, the gas pressure is destroyed, hence the brake shoes 44 are no longer maintained in frictional contact with cylinder I, so that on the counter-recoil stroke the tube and breech cap assembly move forward with a minimum of frictional resistance.

When breech cap 35 moves rearward, the hammer 82 is engaged in cam cut 42 in the breech cap and is thereby cammed downward to a horizontal position, beingrcaught and held in that position, clear of the breech cap 35 by engagement with sear 84 until again released through action of trigger 8I.

While the invention is illustrated in connection with a shoulder mortar, it is to be distinctly understood that the invention is equally applicable to rearms of a size greater than can be operated manually, including all sizes of nrearms in which recoil energy has to be dissipated i by auxiliary means.

of such energy dissipating means.

I claim:

1. A rearm comprising in combination, a housing, a tube member slidably mounted in said housing, a breech cap secured on one end of said tube member, said tube member` dening a firing chamber, said breech cap having a chordal slot therein and a radially disposed recess adjoining the center of said chordal slot, said recess communicating with said ring chamber, and a brake shoe having an arcuate outer bearing surface, said brake shoe having an opening therein, a piston disposed within said opening, said brake shoe and said piston being slidably mounted within said chordal slot and its adjoining radial recess respectively, said brake shoe and said piston being constructed and arranged so that gas pressure developed in the iiring chamber upon the discharge of a powder charge directly actuates said piston and said brake shoe in a radial direction to frictionally engage said housing and thereby resist the relative sliding movement of said tube member within said housing.

2. A firearm comprising in combination, a housing, a tube member slidably mounted in said housing, a breech cap secured on one end of said tube member, said tube member defining a firing chamber, said breech cap having a plurality of equi-angularly-spaced chordal slots therein and a radially disposed recess adjoining the center of each chordal slot, each of said recesses communicating with said firing chamber, and a plurality of brake shoes, each of said brake shoes having a piston associated therewith, each of said brake shoes and said piston being slidably mounted within a chordal slot and its adjoining recess respectively, each of said brake shoes and said piston being constructed and arranged so that gas pressure developed in said nring chamber upon the ring of a powder charge directly actuates said piston and brake shoe in a radial direction to frictionally engage said housing and thereby resist the relative sliding movement of said tube member within said housing.

3. A shoulder mortar comprising in combination, a housing, a, mortar tube, a breech cap secured on one end of said mortar tube, said mortar tube and said breech cap being slidably mounted in said housing and jointly dening a ring chamber, said breech cap having a pair of oppositely disposed chordal slots therein and a radially disposed cylindrical recess adjoining the center of each chordal slot, each of said cylindrical recesses communicating with said ring chamber, and a pair of brake shoes, each brake shoe having a piston associated therewith and eing slidably mounted within one of said chordal slots and its adjoining recess respectively, each brake shoe and said associated piston being constructed and arranged so that gas pressure developed in said firing chamber upon the firing of a powder charge directly actuates said piston and brake shoe outwardhT in a radial direction to friotionally engage said housing and thereby resist the relative sliding movement of said mortar tube and breech cap within said housing.

4. A rearm comprising in combination, a housing, a tube member slidably mounted in said housing, a breech cap secured on one end of said tube member, a brake member provided in said breech cap, said brake member having a piston associated therewith, said brake member being operable by said piston to frictionally resist the,

relative sliding movement of said tube member with respect to said housing, and means for directing gas pressure developed in said tube member upon the ring of a powder charge against said piston for actuation thereof.

5. In a rearm comprising in combination, a housing, a tube member slidably mounted in said housing, a breech cap secured on one end of said tube member, said breech cap having a chordal slot, a brake member slidably mounted in said chordal slot, said brake member having ya piston associated therewith, said brake member being operable by said piston to frictionally resist the relative sliding movement of said tube member with respect to said housing, and means for directing gas pressure developed in said tube member upon the ring of a powder charge against said piston for actuation thereof.

CLARENCE E. SIMPSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 812,326 Browning Feb. 13, 1906 1,809,222 Soncini June 9, 1931 2,067,322 Herlach et al Jan. 12, 1937 FOREIGN PATENTS Number Country Date 304,215 Germany Dec. 30, 1919 792,740 France i Oct. 28, 1935 

